The objectives of this research are the isolation and characterization of the genes encoding the small subunit of ribulose-1,5-bisphosphate carboxylase. We estimate, in pea, that there are approximately five nuclear genes encoding this polypeptide. These genes are efficiently expressed with the small subunit commonly being the major product of leaf cytoplasmic protein synthesis. We plan to isolate all of these genes from pea and to characterize them by restriction analyses, electron microscopi analyses, and sequencing. The chromosomal arrangement of these genes will be examined. From these structural studies we hope to characterize conserved, potential regulatory sequences, which might be involved in the selective expression of these genes. The long term ogjectives of this proposal are to use these genes, and in vitro generated mutants, in both in vitro and in vivo expression studies. From this research, knowledge will be gained concerning the molecular basis of plant genetic systems. Such knowledge is indispensable if plants are to be manipulated to their full potential. This argument holds, whether manipulation is by conventional genetic procedures, or by novel gene-transfer systems.